C—C chemokine receptor type 5 (also commonly known as CCR5 or CD195) is a protein found on the surface of white blood cells. CCR5 acts as a receptor for chemokines and has demonstrated involvement in several different disease states including, but not limited to, human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS). Many strains of HIV, the virus that causes AIDS, initially use CCR5 to enter and infect host cells. A mutation known as CCR5-Δ32 in the CCR5 gene has been shown to protect those individuals that carry it against these strains of HIV. Loss-of-function CCR5 mutants have generated significant interest in the biotech and pharmaceutical industries in light of the widespread and devastating effects of HIV/AIDS (“HIV/AIDS Fact sheet Updated July 2016” from the World Health Organization). However, existing methods and technologies for creating CCR5 loss-of-function mutants in vivo have been ineffective due to the large number of cells that need to be modified. Other concerns involve off-target effects, genome instability, or oncogenic modifications that may be caused by genome-editing treatments.